<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			*{
				margin: 0;
				padding: 0;
			}
			#wrap{
				width: 300px;
				height: 300px;
				margin: 100px auto;
				background: rgba(0,0,0,.5);
				color: #FFFFFF;
				font-size: 30px;
				line-height: 300px;
				text-align: center;
			}
		</style>
	</head>
	<body>
		<div id="wrap">
			我是wrap
		</div>
	</body>
</html>
